In the past, a rear conversion lens is used to magnify the focal length of an image-pickup lens (for example, see Patent Document 1 and Patent Document 2).
Further, as another usage of a rear conversion lens, it is desirable to provide a rear conversion lens, which is to be arranged between an image-pickup lens and a camera having different standards and to be used, in order to use the image-pickup lens and the camera in combination.
For example, there is a need to use a ⅔-inch-format zoom lens with a single-chip color camera including an APS-C size image sensor, and there is a need to use the same ⅔-inch-format image-pickup lens with a super-35-mm-format single-chip cinema camera.
Patent Document 1: Japanese Patent Application Laid-open No. 2005-107261
Patent Document 2: Japanese Patent Application Laid-open No. 2006-349904